Hillary Clinton Got The Biggest Post-Debate Polling Bounce

Hillary Clinton at a “Latinos for Hillary” event on Oct. 15 in San Antonio.

Erich Schlegel / Getty Images

Hillary Clinton got some good news Wednesday, when Vice President Joe Biden announced that he wouldn’t run for the Democratic nomination for president. And she’s testifying before the House Select Committee on Benghazi today. So there’s a lot going on in the news that could affect the polls. But here’s what we know right now: Clinton’s post-debate polling bump looks real.

As might have been expected after the media declared her the winner (more on that below) of the first Democratic primary debate on Oct. 13, Clinton has gained in national and New Hampshire polls (only one post-debate Iowa poll has been released, so we’ll have to wait to know for sure what’s going on there). Meanwhile, Sen. Bernie Sanders has dropped in most polling after the debate.

Before we look at the exact numbers, I’ll note again that a rise in post-debate polls won’t necessarily last. After the Sept. 16 Republican debate, we saw Carly Fiorina climb in the polls only to drop more recently. Additionally, we’re still a few months away from any actual voting. And there’s all that news.

Still, looking at an aggregate of polls gives us a far better picture after the debate than any one poll. With Biden out of the race,1 I’ll be looking only at polls in which Biden was not included or could have his support allocated to the other candidates. If I use the same methodology2 as I have previously to compare pre- and post-debate polls, we can see that the debate worked to Clinton’s advantage among Democrats and those who lean Democratic.

CHANGE IN CANDIDATE SUPPORT, PRE- TO POST-DEBATE

POLLSTER

CLINTON

SANDERS

ABC/Washington Post

+11

-4

CNN/ORC

-1

+5

Emerson

+15

-9

Monmouth

+4

-5

Morning Consult

+2

+2

NBC/WSJ

+5

-5

Average

+6.0

-2.7

Clinton gained in five of the six national polls taken after the debate. This shouldn’t be too surprising: Media spin is what matters most after a debate, and Clinton received very positive coverage. That’s in contrast to her media coverage before the debate, which was very negative. What’s a little bit uncertain is how much ground she picked up. The average has her up 6 percentage points, but CNN found her down 1 point, and the Emerson College poll had her up 15 points.

Sanders, on the other hand, seems to have dropped a little bit, though the picture is muddled. He was down in four polls and up in two. That fits with the idea that Sanders didn’t necessarily do poorly in the debate. Sanders has a well-established ideological base and a group of core supporters who are well-versed in politics and were unlikely to be swayed by the debate.

All told, Clinton has averaged 59 percent to Sanders’s 27 percent in national polls without Biden since the debate. In an average of all polls without Biden in the month before the debate, Clinton was at 53 percent to Sanders’s 29 percent.

Clinton has also gotten a boost in New Hampshire, home to the first primary. New Hampshire has been a weak spot for Clinton. She hadn’t led in a single New Hampshire poll taken in August or September. In fact, Sanders was up by an average of 43 percent to 35 percent in the month before the debate.3 In five New Hampshire polls taken since the Oct. 13 debate, Clinton has led in three to Sanders’s two. On average, they’re essentially tied: Sanders is at 40.6 percent to Clinton’s 40.2 percent.

If Sanders falls behind in New Hampshire, it will be very bad news for his campaign. Not only is New Hampshire right next door to Sanders’s home state, Vermont, it’s also filled with his base voters: white liberals. If Clinton wins New Hampshire, it’s probably a sign that Sanders won’t be competitive in most states outside of Vermont.

Footnotes

Except for when no pollster has conducted a poll within the 30 days before the debate. In that case, I compare the post-debate poll to an average of all polls without Biden over the 30 days before the debate.

When it was available in a poll, I used the question that reallocated Biden supporters to their second choice in both pre- and post-debate New Hampshire surveys.

Harry Enten is a senior political writer and analyst for FiveThirtyEight. @forecasterenten